diff --git a/README.md b/README.md
index c8a2e7b..c5bc63f 100644
--- a/README.md
+++ b/README.md
@@ -29,6 +29,8 @@ Output:
 
 ### CMIP6 (ESGF)
 
+By default, climate-data will search all possible given mirrors for reliability - for endpoints, IDs with mirrors associated in the following form: (`CMIP6.CMIP.NCAR.CESM2.historical.r11i1p1f1.CFday.ua.gn.v20190514|esgf-data.ucar.edu`) should be considered **interchangeable** with mirrorless versions (`CMIP6.CMIP.NCAR.CESM2.historical.r11i1p1f1.CFday.ua.gn.v20190514`). Mirrorless versions should be considered the preferred form. 
+
 #### Search
 
 `/search/esgf`